The misinformation effect: how multiple eye witnesses can make the same mistake

It should come as no surprise to anybody that the witnesses of a crime would often talk to one another straight after the event. A recent survey indicated that 86% of eyewitnesses had discussed the event with co-witnesses straight after the crime had taken place, and why shouldn’t they?

Experiencing a crime is not a routine activity. In most instances, the event happens unexpectedly and can leave eyewitnesses feeling scared and vulnerable. As a result, it is very common for eyewitnesses to be in a state of shock (especially when witnessing a violent crime) and this can leave the individuals turning to others for both reassurance and also for an explanation as to what they had just witnessed. However research indicates that a post-event discussion between co-witnesses can have detrimental effects on the investigation process.

Almost 100 people a year could be convicted of a violent or sexual crime that they did not commit as a result of unreliable eyewitness evidence, according to research conducted by Dara Mojtahedi, an investigative psychologist at the University of Huddersfield – reported on the Justice Gap here.

It is well acknowledged that eyewitnesses can often be wrong in their recollection. Causes for inaccurate statements can stem from eyewitnesses having a poor memory, a less than perfect view of the event or even from being misled by the investigators. Police officers can usually identify if an eyewitness statement is inaccurate if it contradicts the statements of other eyewitnesses who were present. However, according to the New York based Innocence Project in 39% of cases of misidentification, there were multiple eyewitnesses giving the same incorrect statement. The probability of multiple eyewitnesses in an event making the exact same errors in their judgements appears at first glance highly unlikely. Instead, researchers argue that the false recollection of one eyewitness can contaminate the statements of others, if a post-event discussion ensues.

The misinformation effect
To most people, the idea of conforming to misinformation from a co-witness can seem very unlikely, why would anybody take the word of someone else over their own in such a serious setting? What many individuals fail to understand is that during such occurrences, the eyewitnesses who conform to misinformation from others are not consciously aware that they are being influenced by someone else. Instead they would be convinced that they witness the misinformation first hand – leading eyewitness expert Elizabeth Loftus described this act of influence as the misinformation effect.

To understand how the misinformation effect works we must first understand the problems with memory encoding. When exposed to new information, an individual will be able to remember when and where that information was learnt, this is known as source monitoring. However, as time elapses the individual will be less likely to accurately remember the source from which the information was first discovered. Within an eyewitness setting, the memory of the witness will often be distorted (for reasons mentioned above). As a result, there would be gaps within their memory recall of the event. Due to these absences of information, it would become increasingly more difficult later on for eyewitnesses to be able to differentiate between information that they witnessed and information that they were exposed to afterwards. Therefore due to source attribution errors, eyewitnesses who are exposed to a post-event discussion will be at risk of mistakenly reporting misinformation from others in their own statements.

The negative effects of such errors can lead to the conviction and incarceration of innocent individuals. It is worrying then that in 48% of the misidentification cases, the real perpetrator had gone on to reoffend. This statistic can be extremely worrying when we take into account that within the UK, there are over 26,000 cases of violent or sexual crimes per year.

The main point of our research was to create a series of experimental paradigms to observe the behaviours of eyewitnesses when exposed to misinformation. Working under the supervision of Dr Maria Ioannou & Dr Laura Hammond, we were able to make multiple groundbreaking discoveries about the cognitive processes that influence eyewitnesses to conform to misinformation.

We created an eyewitness simulation, where participants would witness a real fight breaking out in a bar. Through the use of actors disguised as participants, the study was able to administrate misinformation to the real participants. The study manipulated the characteristics of the actors as well as the relationship the co-witnesses shared with each other to identify what factors induce memory influence. The emerging results indicate that eyewitnesses will use any available social cues given off by their co-witness to form a stereotypical judgement of their abilities to recall information accurately. This judgement acts as the deciding factor for whether the eyewitness will conform to their misinformation. Additionally the researchers measured the personality traits of participants to determine if certain characteristics increased the participant’s risk of being influenced. The results found that participants who scored highly on being submissive and indecisive were significantly more likely to conform to misinformation.

We are starting to establish what drives an individual to recall false information without being aware of it, however this is just the start. The aim of our work is not to just identify the problem but to help fix it.

The research team aims to start working on policing intervention strategies to help reduce the prevalence of co-witness influence. Research has found that the rapport between the interviewer and the eyewitness a key tool for helping them filter out any misinformation that they did not witness.

About Dara MojtahediDara Mojtahedi is a lecturer in investigative psychology and a PhD candidate with the International Research Centre for Investigative Psychology at the University of Huddersfield's School of Human and Health Sciences